In the last two decades, the biological deodorization was rapidly developed and adopted in various facilities which had odor problems, because it is energy-saving with lower running cost and has the high ability of deodorization. In this paper, the following subjects were respectively investigated: the history of this method, the relating microorganism, the deodorizing mechanism, the characteristics of various existing methods, and case studies of adoptions at many actual facilities. Then, the current studies for development of new advanced methods by biological action were reviewed.
It is considered that this biological method will be generalizing in all the world instead of the physico-chemical methods in the future.

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The spectral method is one of the numerical methods to solve the partial differential equations. In the spectral method, we choose orthogonal function expansions of the dependent variables. The accuracy of spectral method is very high compared to finite difference method and finite element method. However, for non-periodic and uncontinuous initial conditions, spatial oscillations occurs, which may give rise to nonrealistic negative concentrations. The smoothing effects for the spatial oscillations were investigated. For initial condition of delta function form, two smoothing effects of binomial mean smoothing and exponential smoothing in solving the advection equation and diffusion equation are considered in this study.
The binomial mean smoothing was general and stable method. And, the exponential smoothing method has preserved the convection-dominated peaks, and has reduced the dominated negative concentrations. It is shown that the exponential smoothing method is attractive for the spectral solution of uncontinuous initial conditions of delta function form.

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In April, 1983 and May, 1984, visible symptoms of brown spots were observed on potato leaves at the same date in wide areas of Chiba Prefecture. This symptom was similar to the well-known oxidant injury of potato leaves. The degrees of the symptom were quite different in two potato cultivars, Waseshiro and Dan. shakuimo: the injury in the former cultivar was severer than in the latter. The appearance of brown spot symptoms and the difference in sensitivity to ozone between both cultivars were confirmed by filtered air chamber method and ozone exposure experiments in an artificial growth chamber. Therefore, it may be concluded that the brown spots occurred on potato leaves in the crop fields were induced by photochemical oxidants, mainly by ozone. One of the reasons why brown spot symptoms occurred remarkably in 1983 and 1984 was due to the rapid increase of the planting area of Waseshiro, a sensitive cultivar to oxidants.

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Effecst of photochemical oxidants on growth and yields of potatoes were investigated using charcoal-filtered and non-filtered air chambers from April through May of 1984, 1985 and 1987. The degrees of foliar oxidant injury were severer in the cultivar Waseshiro than in the cultivar Danshakuimo. The obtained result was closely similar to that observed at the field survey described in the first report. The shoot weights and tuber yields at the final harvest were greater in filtered air chamber than in non-filtered chamber at both cultivars. There was a linaer relationship different in each cultivar between reduction of potato yield and mean concentration of photochemical oxidants.
Although Danshakuimo was more resistant to photochemical oxidants for the occurrence of foliar injury, tuber yields of the cultivar were reduced to the larger extent than Waseshiro when exposed to higher values of oxidants above threshold concentration. The threshold concentration of oxidants was estimated to be about 0.04 ppm in average value during growing period.

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An automatic automotive emission sampling system for the gas chromatograph (GC) was evaluated to measure the exhaust rate during mode driving of chassis-dynamo test. This system works asfollows:
The exhaust gas was sucked by heated pump and introduced to the vacuum tank (120°C) made by stainless steel. When the inner pressure of tank reached to 1.2 atmospheric pressure, then the sampling was stopped, and sample gas was transfered to the gas sampler of GC using inner pressure of tank.
This system allows the low background measurement so that the hangover rate of automotive emissions in sample tank is minor.
The observed mean value of standard gas which change the concentration imitating the mode driving of test vehicle agreed satisfactory with the calculated value.
To verify the effectiveness of this system, the measurement of formaldehyde and methanol from methanol-and gasoline-fueled vehicles was conducted connecting this system to GC, and analytical values were compared to the values obtained by the reference method. Analytical values of formaldehyde measured by this sampling system-GC method agreed well to that obtained by reference method (DNPH method) within 4%, and analytical values of methanol measured by this sampling system-GC method agreed well to that obtained by reference method (impinger-GC method) within 6%.
Further, in order to grasp the emission characteristics, this sampling system was applied to measure the formaldehyde and methanol in the automotive emissions.

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For the characterization of individual particles in atmospheric dust, the present paper describes the application of an X-ray microanalyzer (XMA) and an X-ray microdiffractometer (XRMD), which consists of a highpower X-ray generator of rotary copper anode type, a three-circle goniometer, a curved position sensitive proportional counter, etc.
Dust fall or airborne particulates was fractionated first with a series of heavy liquids. Then a particle was selected under a microscope using a needle of magnetized stainless steel or copper and stuck on the tip of a handmade sample holder with rubber cement. The particle was set in a three-dimensional motion of the XRMD goniometer and irradiated with a 100 pm collimated X-ray beam. The particles characteristic in shape and color were analyzed and identified from their XRMD patterns. They showed that several substances, such as magnetite, hematite, calcite, and quartz, existed in some different states, which were difficult to be identified from their shapes and colors. Furthermore, the XRMD identified successfully micro constituents such as periclase, mullite, phlogopite, dolomite, rutile, etc., which could not be detected by ordinary X-ray diffraction analysis even using the heavy liquid separation.
The same particles as used for the XRMD were mounted on a flattened pellet of high-purity indium metal and analyzed by an XMA. Obtained elemental information helped the identification of amorphous substances, aggregates of different substances and others, which were difficult to be identified with XRMD patterns.

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In order to evaluate the spa tio-temporal variation of NO₂concentration near the principal roads, a survey was carried out in the vicinity of Kamiuma crossroads of Setagaya. Daily average concentration was measured during a period of five days in March 1989, by using passive samplers (filter badges). Sampling sites were located at the grid points distant 0m, 20m, 50m, 100m and 200m from the roadside of two principal roads crossing at a right angle. Analysis of variance of a three way classification with main effects for days and distance from each road showed the following characteristics.(1) Concentrations went down rapidly at the points of 20m from roadside. Attenuation rate varied with wind direction and speeds, height of roadside buildings and so on.(2) At the roadside, concentration did not decline markedly with distance from the crossroads.(3) Spatialpattern varied by meteorological condition of the day. Daily variation of spatial pattern was large at the area including sites at roadside and 20m distant from roads, and error was large when the daily average concentration at the sites within such area was estimated by using an average spatial pattern and daily average concentration.

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Ion chromatographic (IC) method and zinc reduction-naphthylethylenediamine (Zn-NEDA) method for determination of nitrogen oxides in various flue gases were compared.
It was found that IC method was superior with respect to rapidity, reproducibility and blank value to Zn-NEDA method, and the determination values were very consistent in both methods for measurement of nitrogenoxides in flue gases. The influence of ammonia in gas could be neglected for boiler and ceramics kiln exhaustof residual fuel oil combustion on ozone oxidation/water absorption operation.

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